Breast biopsies are currently performed using a device known as a Core Biopsy System. The Core Biopsy system first obtains a stereo-mammogram from a patient's breast, while the breast is immobilized by being compressed between two plates, and uses these two images to calculate the 3-D coordinates of the suspected tumor. A needle is then fired into the breast and a biopsy is taken of the suspected tumor. If the biopsy is positive, then the patient is scheduled for tumor removal surgery. It should be noted that before the biopsy procedure is commenced, the tumor needs to be manually identified by a radiologist.
The surgical procedure generally proceeds in the following manner. A patient undergoes multi-plane mammography, a radiologist examines the film, and then inserts a wire into the breast so that it punctures the tumor. This procedure is visualized using repetitive x-ray imaging. More recently, the stereotactic breast imaging system has been used to localize the tumor more precisely and assist in the insertion of the wire. The patient is then sent to the operating room, and the breast is prepared for surgery by the application of a topical sterilant. The surgeon then cuts the breast open, following the wire until the lesion is found and excised.
One of the undesirable factors of the foregoing procedure is the presence of a long wire through the breast for many hours at a time while awaiting surgery. This is highly traumatic for the patient and undesirable. Secondly, during surgery, the surgeon must follow the wire into the breast. Since this may not be the optimal trajectory, the surgeon would ideally like to plan the entry pathway independent of the wire, or eliminate the wire altogether. This can be done only if the location of the lesion within the breast can be identified using a system that takes into account the inherent deformability of the breast tissue. It should be appreciated that the problem associated with the deformability of breast tissue applies equally to other easily deformable bodily structures such as the liver.
The current problem limiting use of stereotactic breast surgery is the large difference between the position and shape of the breast during mammography and surgery. In this regard, images taken during mammography become unusable for stereotactic positioning during the surgical procedure. While stereotactic surgery can be done with the breast compressed, and the patient lying on the stereotactic table, this is not desirable. The ideal way to do this surgery is with the patient on her back, as is done routinely.
The present invention overcomes these and other drawbacks of prior art systems and provides a system having significantly improved accuracy and providing greater comfort to the patient.